Performance enhancing athletic shoe components and methods

ABSTRACT

The present invention provides performance enhancing shoe components. The invented shoe component includes an upper layer of 1,4-polybutadiene and, optionally, a rubber such as natural rubber, synthetic isoprene rubber or polyisoprene. The first layer is attached to a resilient layer which extends substantially the length of the shoe. Optionally, a third layer or a coating may be attached to the resilient layer. The invented shoe components may be formed as shoe inserts, insoles, midsoles or shoe soles.

CONTINUITY

This application is a continuation-in-part of U.S. patent application Ser. No. 08/939,782, filed Sep. 29, 1997, abandoned which is a continuation-in-part of U.S. application Ser. No. 08/616,323, filed Mar. 15, 1996, now U.S. Pat. No. 5,695,850, which is a continuation-in-part of U.S. patent application Ser. No. 08/409,023, filed Mar. 23, 1995, now U.S. Pat. No. 5,554,694.

I. BACKGROUND OF THE INVENTION

A. Field of Invention

The invention relates to the field of performance enhancing shoe components and methods for making the same. More specifically, this invention relates to the field of performance enhancing shoe components which provide energy return and improve athletic performance, and methods of making the same.

B. Description of the Related Art

There is a high demand for athletic equipment which enhances the performance of athletes. As athletic events become more competitive, small improvements in performance become increasingly important. Athletic equipment which enhances the performance of athletes by only a few tenths or hundredths of a second, or a fraction of a centimeter, may provide the "winning edge" sought by athletes. For this reason, athletes are constantly seeking equipment which will improve their performance. The designs of all types of equipment from bicycles to tennis rackets are constantly scrutinized for features which may improve performance. For example, racing bicycles have been radically redesigned to improve performance while reducing weight and friction. Cycling helmets have also been redesigned to reduce weight and wind resistance.

This high demand for performance enhancing athletic equipment includes the art of athletic shoes and shoe components. Various features have been included in shoes for promotional reasons or for comfort. Most improvements in athletic shoes have been made in the physical and structural composition of the interior and exterior elements of soles of athletic shoes to improve the comfort and appearance of the shoes. While it has long been desired to produce athletic shoes which provide meaningful increases in athletic performance, few, if any, changes in athletic shoes have produced measurable improvements in performance. Often an improvement in athletic shoe performance is sought but is not attained because the design of the resulting shoe becomes a compromise between comfort and cost. No prior shoe features provide substantial energy return to the user. Similarly, prior shoe features did not provide energy return in the form of lift, spring or bounce.

The material most frequently used for insoles in athletic shoes is ethylene vinyl acetate ("EVA"). EVA is a lightweight, inexpensive, sponge-like material which does not provide significant energy return. Examples of shoe insoles made from EVA are disclosed in a U.S. patent to Fujita et al. (U.S. Pat. No. 4,418,483), which is incorporated herein by reference. This patent teaches making shoe midsoles by combining EVA with a styrene-butadiene rubber. While such midsoles have excellent cushioning properties, they do not enhance athletic performance by providing energy return to the user. Rather, the cushioning effect of the EVA material reduces athletic performance by absorbing energy.

Fujita et al. also disclose combining 1,4-polybutadiene with other rubbers, such a 1,2-polybutadiene, to make hard shoe outsoles or shoe midsoles. These other rubbers do not provide substantial energy return, and these rubbers reduce the energy return characteristics of the 1,4-polybutadiene. For example, in its cured state, 1,2-polybutadiene is a hard material which lacks the ability to be compressed and rebound to provide energy return. In its uncured state, 1,2-polybutadiene (syndiotactic) may exhibit mild elastomeric properties. When high energy return rubbers such as 1,4-polybutadiene rubber are combined with 1,2-polybutadiene, the 1,2-polybutadiene typically controls the characteristics of the resulting composition and reduces its energy return. Similarly, Fujita et al. teach the inclusion of fillers such as hard clay and silica, which further reduce the energy return of the shoe component.

A U.S. patent to S. P. Chang and R. I. Chang (U.S. Pat. No. 5,147,589), which is incorporated herein by reference, discloses a method of making shoe soles of a polymer blend which is a mixture of rubbers including thermoplastic elastomers, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and plastics such as polystyrene, EVA, or polyvinyl chloride. When high energy return rubbers such as 1,4-polybutadiene rubber are incorporated into such shoe soles, the high energy rubbers compose only a small weight percentage of the total rubber in the shoe, and, therefore, the shoes do not provide substantial energy return. Chang et al. also teach the inclusion of non-energy returning materials ("fillers"), including white hard clay, white carbon VN-3 filler, carbonates and silica. These materials will modify some characteristics, such as durability or strength, of the shoe part, but will also decrease energy return.

A U.S. patent to T. Noyama and A. Nakahara (U.S. Pat. No. 5,288,446) discloses a process for imparting strength to rubber articles. This patent is incorporated by reference herein. Noyama et al. teach enhanced strength by adding fillers such as metal salts of alpha, beta-unsaturated fatty acids, nylon and calcium carbonate. Such fillers harden the rubber article and improve its strength at the expense of energy return. Because such hardened compositions are less compressible, they can injure the user.

A U.S. patent to Sullivan et al. U.S. Pat. No. 4,910,886) discloses a shoe insert for total shock absorption, but not for energy return. This patent is incorporated by reference herein. The innersole of Sullivan et al. contains predominant amounts of a substantially non-deformable, expandable polymer, such as elastomeric urethane. Such materials are not known for providing energy return or for improving athletic performance.

While the energy return of 1,4-polybutadiene, in the form of super balls, for example, is known, those of ordinary skill in the shoe art have not looked to shoe components made of 1,4-polybutadiene and other high energy return rubbers to improve athletic performance. The makers of athletic shoes have failed to appreciate the significant energy return available from shoe components of 1,4-polybutadiene in combination with other high energy return rubbers such as natural rubber, synthetic isoprene rubber, polyisoprene, butadiene acrylonitrile rubber or ethylenepropylene diene modified rubber.

II. SUMMARY OF THE INVENTION

The present invention provides a shoe component, and a method for making the shoe component, which significantly enhances athletic performance when placed within a shoe. The shoe components also possess both durability and tensile strength.

It is an object of the present invention to provide shoe components, such as insoles and midsoles and soles, which significantly improve an athlete's ability to leap forward, jump upward, and run faster. It is a feature of the invention that the shoe components provide improved athletic performance. It is an advantage of the invention that the shoe components can improve athletic performance in a variety of athletic events.

It is an object of the invention to provide a variety of shoe components which improve athletic performance. It is a feature of the invention that the shoe components may comprise a sole, a sole portion, a midsole, a midsole portion, an insole, an insole portion or an insert which possesses significant energy return characteristics. It is an advantage of the invention that the shoe components may be designed to fit a variety of athletic shoes and may be positioned within the sole, at the midsole, at the insole, or on top of the insole. It is a further advantage of the invention that the shoe components are light-weight.

It is an object of the invention to provide shoe components which increase an athlete's stride length. It is a feature of the invention that the shoe components can increase stride length. It is an advantage of the invention that longer stride lengths can help athletes run faster. It is a further advantage of the invention that the shoe components can also reduce leg fatigue.

It is an object of the invention to provide shoe components of a soft, high energy return material which also provides shock absorption. It is a feature of the invention that the shoe components are fully compressible by the human foot to maximize energy return. It is an advantage of the invention that the shoe components are a soft-high energy return material which prevents injury to the human foot. It is a further advantage of the invention that the shoe components provide energy return, cushioning, and comfort to athletes as well as non-athletes.

It is an object of the invention to provide a shoe component that can be used by injured athletes. It is a feature of the invention that the shoe components provide cushioning and shock absorption to prevent further athletic injuries. It is an advantage of the invention that the shoe components help prevent injuries and help rehabilitate athletes with injuries such as shin splints.

These and other objects, features and advantages of the invention will be clear to a person of ordinary skill in the art upon reading this specification in light of the appending drawings.

III. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective representation of an athletic shoe having an internal sole portion comprising one embodiment of the present invention.

FIG. 2 is an enlarged fragmentary perspective shown partly in cross-section of an insole of the present invention.

FIG. 3 is a perspective of an insole or midsole of another embodiment of the present invention including a neoprene pad and a 1,4-polybutadiene/rubber layer.

FIG. 4 is a perspective of an insole or midsole of another embodiment of the present invention including a 1,4-polybutadiene/rubber layer connected to sections of a neoprene pad.

FIG. 5 is an enlarged fragmentary cross-section of an embodiment in accordance with the present invention with a sole element inserted into a cavity in the sole.

FIG. 6 is an enlarged fragmentary cross-section of an embodiment of this invention.

FIG. 7 is an exploded perspective of two separate, superimposed insole portions comprising slits for expansion under compression, which are adapted for placement within a shoe at either the ball, the heel or both.

FIG. 8 is a perspective of an insole portion having breathing and yawning perforations, adapted for placement within a shoe at either the ball, the heel or both.

FIG. 9 is a fragmentary side elevation partly in cross-section showing a sole element within the insole region sandwiched between relatively rigid top and bottom layers.

FIG. 10 is a fragmentary side elevation partly in cross-section similar to FIG. 9, but with the insole disposed between relatively rigid top and bottom layers within the sole region substantially as close as reasonably possible to the exposed bottom tread surface of the shoe.

FIG. 11 is a fragmentary perspective of a shoe showing a high bounce lamination within an insole or mid-sole region of the shoe.

FIG. 12 is a section of one embodiment of the sole element taken across the shoe of FIG. 11 at the instep.

FIG. 13 is a cross-section of another embodiment of the sole element similar to FIG. 12.

FIG. 14 is a cross-section of another embodiment of the present invention.

FIG. 15 is a cross-section showing another embodiment of the invention having three layers.

IV. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invented performance enhancing shoe components include a sole, a portion of a sole, a midsole, portion of a shoe midsole, an insole, a portion of an insole, or a shoe insert. As used herein, the term "performance enhancing" means that the shoe component permits the wearer to jump higher, leap farther, run faster, take longer strides, etc.

A. Composition of the Present Invention

The invented shoe components include a mixture of 1,4-polybutadiene and a high-energy return rubber. As used herein, the term "1,4-polybutadiene" is a 1,4-polybutadiene having a cis content of at least about 90%. More preferably, the 1,4-polybutadiene has a cis content of at least about 95%, which is referred to hereafter as "high-cis 1,4-polybutadiene." In the most preferred embodiment of the invention, the invention comprises a 1,4-polybutadiene having a cis content of at least about 98%, which is referred to hereafter as "very high-cis 1,4-polybutadiene."

When making the invented shoe component, the 1,4-polybutadiene is combined with a high-energy return rubber such as natural rubber, synthetic isoprene rubber, polyisoprene, butadiene acrylonitrile rubber and ethylenepropylene diene modified rubber. These rubbers provide substantial energy return in combination with the 1,4-polybutadiene. The most preferred rubber is natural rubber, such as standard Malaysian rubber, Grade 5.

Methods of preparing and determining the cis content of 1,4-polybutadiene, and of making cured mixes of 1,4-polybutadiene with other rubbers, are well known to those of ordinary skill in the art. Such methods are disclosed in the Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition), which is incorporated herein by reference.

Typically, the 1,4-polybutadiene/rubber blends used in the invention will be characterized by an amount of 1,4-polybutadiene within the range of about 46 to about 100 weight percent and an amount of rubber within the range of about 54 to about 0 weight percent, based on the total weight of the 1,4-polybutadiene and the rubber. In a more preferred embodiment of the invention, the amount of 1,4-polybutadiene may range from about 75 to about 100 weight percent and an amount of rubber within the range of about 25 to about 0 weight percent, based on the total weight of the 1,4-polybutadiene and the rubber. In a still more preferred embodiment, the amount of 1,4-polybutadiene may range from about 85 to about 100 weight percent and an amount of rubber within the range of about 25 to about 0 weight percent, based on the total weight of the 1,4-polybutadiene and the rubber. In the most preferred embodiments of the invention, the inventor has discovered that increasing the proportion of 1,4-polybutadiene in the invented composition further improves energy return; in this embodiment, the amount of 1,4-polybutadiene may range from about 95 to about 100 weight percent, and the rubber may range from about 5 to about 0 weight percent.

Examples of embodiments of the present invention will include those presented in Table 1. As the percentage of the 1,4-polybutadiene increases with respect to the rubber, energy return increases and durability and tensile strength decrease.

Referring to Table 1, Example 1 will be a substantially solid shoe sole of about 46 weight percent 1,4-polybutadiene and about 54 weight percent polyisoprene, which will provide energy return as well as shock absorption. A foam insole (Example 2) will include equal parts of 1,4-polybutadiene and butadiene acrylonitrile rubber. Such a shoe insole may be used by wearers seeking a comfortable insole which provides energy return. Shoe midsoles and insoles which will provide enhanced energy return as a result of a cured mix of high-cis 1,4-polybutadiene and a rubber are shown in Examples 3, 5, 7, 9 and 10. Examples of shoe insoles and midsoles made of a cured mix of very high-cis 1,4-polybutadiene and natural rubber will include Examples 11-14.

A foam insole providing enhanced energy return (Example 4) will include about 75 weight percent 1,4-polybutadiene and about 25 weight percent synthetic isoprene. In some embodiments of the invention, the shoe component will include a foam midsole with about 95 weight percent 1,4-polybutadiene and about 5 weight percent of a rubber such as natural rubber (Example 6). In a more preferred embodiment of the invention, the invention is a substantially solid insole of about 60 weight percent of high cis or very high-cis 1,4-polybutadiene and about 40 weight percent natural rubber (Examples 8 and 11).

In other preferred embodiments of the invention, the 1,4-polybutadiene may contain other materials such as stabilizing agents. Such a 1,4-polybutadiene may include FIRESTONE DIENE 55NFA or FIRESTONE DIENE 55AC10, which typically have a cis content of about 90%. Alternately, the invention may comprise a high-cis 1,4-polybutadiene such as FIRESTONE DIENE 600, 635, 645 or 660, which have a typical analysis of about 95% cis content. In a still more preferred embodiment of the invention, the 1,4-polybutadiene is very high-cis 1,4-polybutadiene, such as Goodyear BUDENE 1207 or 1208; another suitable rubber is KBR01, which is about 95-98% cis.

The 1,4-polybutadiene may be combined with a high energy return rubber selected from the group consisting of natural rubber, synthetic isoprene rubber, polyisoprene, butadiene acrylonitrile rubber and ethylenepropylene diene modified rubber to form a pre-mix. The pre-mix is then cross-linked to form a cured mix, hereafter referred to as a "1,4-polybutadiene/rubber composition." To accomplish this, well known additives are introduced into the pre-mix. Specifically, activating, accelerating, and curing agents are introduced as part of the pre-mix, as will be discussed in more detail below.

In one preferred embodiment of the invention, a foaming agent (blowing agent) may be included in the pre-mix to form a foam composition containing entrapped gas. The type and use of such foaming agents are readily known to those of skill in the art. The amount of foaming agent may include any effective amount of foaming agent sufficient to form a foam 1,4-polybutadiene/rubber composition. Such an effective amount may range from about 0.1 to at least 20 weight percent, based on the weight of 1,4-polybutadiene and rubber. In another preferred embodiment of the invention, the cured mixture may be substantially solid and free of trapped gas by omitting a foaming agent. Agents such as activation, acceleration and curative agents may be used in the preparation of either the foam or substantially solid 1,4-polybutadiene/rubber composition.

B. Shoe Components of the Present Invention

Reference is now made to the drawings wherein like numerals are used to designate like parts throughout and which illustrate various forms and embodiments of the present invention, as are currently preferred. For the following discussion, the term "1,4-polybutadiene rubber composition" includes 100% polybutadiene compositions.

FIG. 1 illustrates a typical athletic shoe, generally designated 30, which is intended to exemplify any conventional shoe (athletic or otherwise) equipped with a shoe sole embodiment of the present invention. Shoe 30 comprises a conventional upper portion, generally designated 32, which comprises a foot-receiving interior 34, a tongue 36, laces 38, and lace-receiving apertures 40 disposed in opposed, spaced, reinforced bands 42 located at the arch of the shoe.

Shoe 30 also comprises a sole, generally designated 44. Sole 44 is connected to upper shoe portion 32 at lap interface 46 in any desired conventional way, such as by heat fusion, adhesive bonding and/or stitching.

Sole 44 is illustrated as comprising vertical side surfaces 48 and a bottom tread surface 50. The sole 44 is illustrated as spanning from the toe 54 to the heel 56 of the shoe and is configurated along side surfaces 48.

Referring to FIG. 2, the 1,4-polybutadiene/rubber composition can form an insole layer 150 within a shoe 30, which runs the full length of the shoe and is configurated as is the shoe. The insole 150 is illustrated as being of uniform thickness throughout its entire length and comprises a top surface 62 and a bottom surface 64. The insole 150 may also form part of an insole to be positioned at any desired location, such as at the ball region or the heel region, for example. The 1,4-polybutadiene/rubber composition can also form a midsole layer, or a portion thereof, or a shoe insert in shoe 30.

The thickness of the layer may range from about 1/32" to about 1/2". In the preferred embodiment of the invention, the thickness of the layer may range from about 1/16" to about 1/4". In the most preferred embodiment of the invention, the thickness of the layer is about 5/64". To achieve the highest energy return, it is important for the user to nearly or completely compress the 1,4-polybutadiene/rubber composition and then to allow the composition to expand or rebound to its original thickness. Therefore, the thickness of the shoe component may also be varied according to the weight and strength of the user.

Referring to FIG. 3, the 1,4-polybutadiene/rubber composition can be combined with a larger pad 360 to form a shoe insole, midsole or shoe insert 350. The pad is preferably also a high energy return material such as neoprene, natural rubber, foamed urethane or an EVA/natural rubber mixture. For EVA/natural rubber pads, the amount of EVA may range from about 25 to about 75 weight percent and the amount of natural rubber may range from about 75 to about 25 weight percent, where the weights percentages are based on the total amount of EVA and natural rubber. For a natural rubber pad 360, a preferred natural rubber is LINATEX 95% natural rubber (Linatex, Inc., Phoenix, Ariz.), a low-temperature cured rubber.

In a more preferred embodiment of the invention, a 1,4-polybutadiene/rubber composition 355 is superimposed on a layer of pad, such as neoprene (RUBATEX 8536; Rubatex, Longbeach, Calif.), so that the 1,4-polybutadiene/rubber composition is positioned under the ball of the wearer's foot.

In a still more preferred embodiment of the invention, the 1,4-polybutadiene/rubber composition 355 is inserted into channel 351 in the pad 360. Channel 351 is preferably formed by cutting a channel with an abrasive sanding disc. Channel 351 is preferably about 31/2 inches wide, 1/32 inches deep and centered under the ball of the ball of the foot. Channel 351 may be formed in the top or bottom of pad 360. In the most preferred embodiment of the invention, channel 351 is formed in the bottom of pad 360.

In the most preferred embodiment of the invention, the area of the pad which will be placed beneath the ball of the foot is compressed prior to forming channel 351. The pad may be compressed by any suitable compression means including, but not limited to, a hydraulic press. The pad is compressed to between about 15 to 90 tons for about 2-3 seconds, although shorter or longer compression times are within the scope of the invention. In a more preferred embodiment of the invention, the pad is compressed to between about 15 to 45 tons, preferably 30 tons (about 8500 psi), of pressure. Such compression prior to forming channel 351 further increases the energy return of the 1,4-polybutadiene/rubber/pad composition. The energy return of the combination is tested by dropping a heavy round object, such as a super-heavy basketball (about 5 pounds), on the pad from a height of about 7 feet. An increase in energy return of about 6-8% is observed as compared with an uncompressed pad.

The 1,4-polybutadiene/rubber composition can be attached to the pad by any suitable attachment mechanism, including but not limited to, heat fusion and gluing. Referring to FIG. 4, the 1,4-polybutadiene/rubber composition 355 can also be attached between sections of high energy return material 368. The 1,4-polybutadiene/rubber composition 355 can be attached to neoprene sections 368 by any suitable attachment mechanism, including but not limited to, heat fusion and gluing. Referring to FIG. 5, sole inserts also fall within the scope of the present invention. Specifically, the tread portion 44' of athletic shoe 30 is illustrated in FIG. 5 as having a rectangular recess 152 disposed at the upper surface thereof. A sole insert 154 of a 1,4-polybutadiene/rubber composition is illustrated as having been placed into the recess 152 so that the edges thereof are flush with the top surface of the tread portion 44 while the arched center 156 of the sole insert protrudes above the tread portion towards the wearer's foot. Other configurations could be used such as a flat or convex sole segment for insert 154. The sole insert 154 can be disposed in the interior of the shoe at any desired location, such as at the ball region, the heel region or the arch region, for example. Furthermore, either in a localized or comprehensive way, embodiments wherein a portion thereof is within a shoe at the sole region thereof and/or a portion is exposed exterior of the shoe are also within the scope of the present invention.

When the 1,4-polybutadiene/rubber composition is disposed in the bottom of a shoe sole, the composition is preferably coated with a thin, abrasion-resistant material which prevents wearing away of the 1,4-polybutadiene/rubber composition. Such abrasion resistant materials may include, for example, a thin layer of 1,2-polybutadiene.

Referring to FIG. 6, sole 44 of the shoe 30 may be fashioned so as to comprise an internal recess 250. The described insert 230 may be installed within the recess 250 either with the serrations up or down, as desired, the serrations being illustrated as disposed in a downward direction in FIG. 6. The insert 230 is secured by heat fusion, adhesive material or in any other suitable way within the recess 250 and may be so secured so as to be removable and replaceable with a new sole segment in accordance with the principles of the present invention when and as desired. A spacer material, if desired, may be juxtaposed with the serrated surface 222, or not used at all, as illustrated in FIG. 6.

In a preferred embodiment, the 1,4-polybutadiene/rubber composition may have surface texturing. Such texturing is desirable to prevent slippage of the composition in a shoe, to promote adhesion between layers, and may also provide additional energy return. Such texturing is preferably formed during a calendering process, as will be appreciated by those of skill in the art.

The 1,4-polybutadiene/rubber composition may also have corrugations, ripples, wrinkles or folds (hereinafter "corrugations"). Such corrugations both prevent the composition from slipping in the shoe and also provide additional energy return and shock absorption. When a force is applied to such a composition, the corrugations compress or flatten, thereby absorbing energy. When the force released, the corrugations spring back to their original shape, providing additional mechanical energy in addition to the resilient energy inherently provided by the 1,4-polybutadience/rubber composition.

When the 1,4-polybutadiene/rubber composition includes additional layers or coating, the corrugations are preferably included in the additional layers or coating.

Such corrugations may be formed in the manufacturing process. For example, if the material is loosely wrapped during the calendering process, corrugations will form. Corrugations may also be formed in the 1,4-polybutadiene/rubber composition using a mold and press.

Referring to FIG. 7, a bi-layer insole portion, generally designated 260, may be fashioned in accordance with the principles of the present invention. The insole portion 260 comprises the top layer 262 and bottom layer 264, each comprising one of the above-described 1,4-polybutadiene/rubber compositions in accordance with the principles of the present invention. In use, insole segment layers 262 and 264 are intended to be vertically superimposed and contiguous one with the other and to be placed beneath either or both the ball or heel of a foot of a user within the interior of a shoe. The insole layers 262 and 264 may be placed either above an existing insole layer or within a recess internally disposed within the shoe having a suitable thickness to accommodate receipt of layers 262 and 264.

Layer 262 is illustrated as comprising longitudinally directed fingers cut in the material after it is formed and cured. These fingers, are formed by a plurality of alternate slits 266 which extend from a location slightly spaced from the front edge 268 to intersect the rear edge 270.

Similarly, at locations mid-distant between slits 266 are disposed additional longitudinally directed slits 272, which begin at a location slightly forward of the rear edge 270 and extend in a forwardly direction terminating at forward edge 268.

The slits 266 and 272 form a series of opposed rearwardly and forwardly extending fingers such that when subjected to weight and the force of walking or running under the ball or heel of the user's foot will accommodate yawning, spreading or separation of the fingers at the slits 266 and 272 to enhance energy return in a desired direction. Similarly, insole segment layer 264 comprises a blunt left side edge 274 and a blunt right side edge 276 (as viewed in FIG. 7). Transfer slits 278 extend from edge 274 to a location in each case spaced a short distance from edge 276. Similarly, transverse slits 280 extend entirely through layer 264 and run from edge 276 to a location spaced a short distance from edge 274.

Just as slits 266 and 272 in partial insole layer 262 yawn, spread or expand transversely to improve energy return, so too do slits 278 and 280 yawn, spread or expand under weight and force in a longitudinal direction to similarly improve energy return or rebound of the bi-layer insole segment 260.

Reference is now made specifically to FIG. 8, which illustrates still another insole segment, generally designated 290, formed in accordance with the principles of the present invention. Insole segment 290 is illustrated as comprising front and back blunt edges 292 and 294 as well as curved left and right side edges 296 and 298, so that the insole segment 290 may be placed beneath the heel and/or ball of the foot of the user in a shoe for improved energy return in a desired direction, such as at an angle to both the horizontal and the vertical. The increase in energy return not only improves the distance one can jump, but adds an increment of quickness to each step or stride of the user.

The insole segment 290 comprises a plurality of perforations or apertures 300, which allows any shoe portion disposed below the insole segment 290 to breathe and which also provides room for the material comprising the insole segment 290 to expand or spread under the weight and force of the user during walking and running. By providing space in the form of perforations 300 for the flattening of the insert segment 290, the energy return is enhanced.

Reference is now made to FIG. 9 which illustrates still a further embodiment, generally designated 310, of the present invention. The shoe embodiment 310 comprises a shoe upper 312, an interior insole 314, and a tread layer 316.

While shoe 310 and the components described above are intended to be representative of any shoe incorporating the invention, the configuration or arrangement of FIG. 9 is illustrative of principles pertaining to the present invention. Specifically, above the top surface 318 of the exposed tread layer 316, adjacent the ball receptacle of the shoe 310, is disposed a lower recess 320 in the midsole 314. A sole segment 322 is disposed with the recess 320 and is, therefore, spaced from the sock and shoe of the user. Segment 322 may be substantially rectangular in configuration and is illustrated as having a uniform thickness throughout. Segment 322 may also have any other suitable configuration according to the desired use and placement of the segment within the midsole. The segment 322 is illustrated as entirely filling the lower cavity 320 in the midsole layer 314. The segment 322 is illustrated as comprising one of the above-described foam 1,4-polybutadiene/rubber compositions, although segment 322 can also be formed of a substantially solid 1,4-polybutadiene/rubber composition.

The configuration illustrated in FIG. 9 is such that the midsole layer 314, and particularly that reduced thickness portion 324 of midsole 314 disposed immediately above the insole segment 322 is preferably relatively stiff. The midsole layer, therefore, tends to maintain its flat configuration and function as a bearing plate when the weight of the user and the force of the user's foot in walking and running are imposed thereon to compress the layer 322. When the exposed tread sole 316 is also relatively stiff and resistant to material indentation it functions also as a bearing plate whereby the layer 322 is compressed between two relatively stiff bearing plates. As the weight and force of the user's step or stride is lifted, it has been found that the energy return of the layer 322 against the foot of the user enhances stride and lift. While the configuration of the layer 322 is illustrated in FIG. 9 as being limited to the ball of the foot of the user, it is to be appreciated that it could be extended beyond the ball of the foot and/or placed under the heel of the user or under both the ball and heel of the foot of the user.

Reference is now made to FIG. 10 which illustrates an additional shoe embodiment, generally designated 310'. Shoe 310' includes upper shoe portion 312, a relatively thin insole layer 314' and a sole 316'. The insole 314' is illustrated as being of uniform thickness throughout and without any recess or cavity disposed therein. In other preferred embodiments of the invention, the thickness of insole 314' could be varied according to the desired use and performance enhancement. The exposed sole 316' may comprise a generally rectangular shaped cavity 320' disposed between the bottom surface 330 of the insole 314'. The thickness of the cavity 320' is illustrated as being uniform and slightly greater than one-half the depth of the sole 316' both forward and rearward of the cavity 320'. The thickness of 320' may also be varied according to the desired use and performance enhancement. The layer 322, described above in connection with FIG. 9 is illustrated as being disposed within cavity 320' and serves to function in the same fashion described above when interposed between a stiff plate-like insole 314' and a reduced thickness sole layer 322 so that the 1,4-polybutadiene/rubber composition of layer 322 is essentially sandwiched between two stiff plates. Thus, as force due to weight, walking and/or running is cyclically applied and removed by the foot of the user to the top plate, i.e., stiff insole 314', the layer 322 is compressed and recoils between layers 332 and 314'. Thus, when the force and weight are lifted by the user, the recoil effect of the layer 322 is imposed in a somewhat uniform way across the entire ball or other part of the foot and provides energy return.

FIGS. 11 and 12 illustrate a shoe 380 comprising an upper portion 382, and a sole portion, generally designated 384. Sole 384 comprises a midsole or insole layer 390 and a bottom sole 388. Insole or midsole 390 is a lamination comprising two layers of foot-supporting materials, top layer 398 and a bottom layer 400. Top layer 398 is preferably a thin layer or coating of a resilient or semi-rigid material on the top surface of the 1,4-poly-butadiene/rubber composition 400, hereafter referred to as a "coating". The coating serves to provide more uniform compression of the underlying layer 400, especially at the region underneath the ball of the foot. Referring to FIG. 15, when the toes exert a force on an area of coating 398, coating 398 is adapted to transmit at least a portion of that force to a greater surface area of layer 400, which underlies coating 398. Through this action, coating 398 facilitates compression of a larger area of layer 400 than is compressed by the wearer's toes. Coating 398 also aids in compressing underlying pad 400 more quickly to provide faster rebounding action.

In a more preferred embodiment of the invention, a natural rubber, neoprene, styrene butadiene rubber or polyurethane coating is used. Natural rubber is most preferred a because it has more tensile strength than the 1,4-poly-butadiene/rubber composition, and thereby give more tensile strength to the entire composition. The preferred natural rubber is a high durometer rubber with good tensile strength. The coating thickness may range from about 1/64" to about 3/32". In the most preferred embodiment of the invention, the coating thickness is about 1/2" to 1/64". The coating thickness may be varied according to the desired use of the shoe component, as will be appreciated by those of skill in the art.

The coating, which can be applied as a thin layer, is tightly bonded to the top surface of the bottom layer 400. Bottom layer 400 comprises the above-described 1,4-polybutadiene/rubber composition.

Such a coating functions by causing the layer to more uniformly compress when a force is applied, as described above. Other suitable coatings may include a mesh of cloth, fiberglass or thin metal, screen of cloth, fiberglass or thin metal, and thin resilient or semi-rigid plastics.

In another preferred embodiment, a coating can be used in combination with a high percentage 1,4-polybutadiene composition. Such a composition can include from 75% up to 100% 1,4-polybutadiene, with the balance comprising a rubber. In addition to providing compression of a larger area of the composition, and providing faster rebound, the coating also serves to increase the wear resistance of the high percentage 1,4-polybutadiene composition.

In another preferred embodiment, additional layers of resilient material may be placed on top of the 1,4-polybutadiene/rubber composition. Such additional layers may include styrene butadiene rubber, neoprene, polyurethane and other resilient materials. Such additional layers function by causing lower layers to more uniformly compress when a force is applied, as described above. Such additional layers may range in thickness from 1/6" to 3/32," although thinner or thicker layers are also within the scope of the invention. In the most preferred embodiment, the composition includes a layer of styrene butadiene rubber on a layer of natural rubber on the 1,4-polybutadiene/rubber composition. Suitable type of styrene butadiene rubber include Rubatex 8514 and 8515.

Referring to FIG. 13, insole 410 can also be used. Insole 410 is similar to insole or midsole 390, except a second coating 412 is disposed contiguously with the bottom surface of the layer 400. Layers 398 and 412 may comprise the same materials or different materials. Layers 398 and 412 may have the same or different thicknesses.

When the 1,4-polybutadiene/rubber composition has additional layers or coatings, the resulting shoe component may be either a pad placed beneath the ball of a human foot, or a full-length shoe insert. Such pad or insert may be an insole, may be placed under an insole, or as a midsole. For example, a full length shoe component may include a styrene butadiene rubber layer, on a layer of natural rubber, on a layer of 1,4-polybutadiene/rubber or 1,4-polybutadiene alone. A full length shoe component may also include a natural rubber layer on a layer of 1,4-polybutadiene/rubber or 1,4-polybutadiene alone. In another embodiment, a full length insert may include a layer of styrene butadiene rubber layer on a layer of 1,4-polybutadiene/rubber or 1,4-polybutadiene alone. This embodiment may further include a layer or coating of natural rubber located between the outer layers and placed beneath the ball portion.

Referring to FIG. 14, in another preferred embodiment of the invention, the invented shoe component 500 includes first and second layers of 1,4-polybutadiene/rubber composition 505 separated by a coating 510. The coating 510 may be adhesively attached or bonded to one or both of 1,4-polybutadiene/rubber layers 505. As discussed above, the coating serves to provide more uniform compression of the lower 1,4-polybutadiene/rubber layer. The coating may also serve as a bearing plate to compress the lower layer and provide better rebound for both the lower and upper layers, as described above.

The invented shoe component may also include two layers of 1,4-polybutadiene/rubber composition. For example, each layer can be about 80 weight percent very-high cis 1,4-polybutadiene and about 20 weight percent natural rubber. Each layer is about 5/64 inches thick. The 1,4-polybutadiene/rubber layers are separated by a coating. The combined pad is preferably inserted into a channel 5/64 inches deep and 31/2 inches wide in a 3/16 inch thick pad of neoprene (RUBATEX 8536), or an EVA/natural rubber insole. The channel is formed by cutting the pad with a sanding disc. Prior to forming the channel, the area of the pad which will be placed beneath the ball of the user's foot is compressed in a hydraulic press for 2-3 seconds to a pressure of about 30 tons. The 1,4-polybutadiene/rubber composition is attached to the neoprene pad by gluing. A layer of elastic fabric, ribbing, is attached to the pad by gluing with a neoprene-based glue, as discussed below.

Another exemplary embodiment is a 90%/10% 1,4-polybutadiene/natural rubber pad, about 1/16" thick, which has a 1/32" high durometer natural rubber coating bonded to its top surface. The 1,4-polybutadiene/natural rubber mix is preferably formed from a recipe containing 6 lbs of sulfur per 100 lbs or 1,4-polybutadiene and natural rubber. The cross-linked mixture is calendered within one day. The natural rubber coating may be bonded by calendering.

The embodiments of the present invention may be covered with an elastic fabric such as ribbing. In a preferred embodiment of the invention, the ribbing is an elastic neckband material. The elastic fabric may be attached to an embodiment of the invention using a suitable bonding agent. In the most preferred embodiment of the invention, the bonding agent is a neoprene-based glue.

C. The Methodology

The methodology by which the athletic performance-enhancing shoe components of this invention are formed is also significant. Persons of skill in the art will appreciate that the following recipes may be readily varied to make compositions having other 1,4-polybutadiene/rubber ratios.

One preferred, substantially solid 1,4-poly-butadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber           40.00                                                 1,4-Polybutadiene (FIRESTONE DIENE 55NFA)                                                               60.00                                                 Zinc Oxide               5.00                                                  Stearic Acid             2.50                                                  2,2'-Dithiobisbenzothiazole                                                                             0.75                                                  Tetramethyl Thiuram Disulfide                                                                           0.40                                                  ______________________________________                                    

FIRESTONE DIENE 55AC10 (1,4-polybutadiene, 90% cis content) may also be used in this embodiment of the invention.

Another preferred, substantially solid 1,4-poly-butadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber           25.00                                                 1,4-Polybutadiene (FIRESTONE DIENE 55NFA)                                                               75.00                                                 Zinc Oxide               5.00                                                  Stearic Acid             2.50                                                  2,2'-Dithiobisbenzothiazole                                                                             0.75                                                  Tetramethyl Thiuram Disulfide                                                                           0.40                                                  ______________________________________                                    

FIRESTONE DIENE 55AC10 (1,4-polybutadiene, 90% cis content) may also be used in this embodiment of the invention.

Another preferred 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber       40.00                                                     High-Cis 1,4-Polybutadiene                                                                          60.00                                                     Zinc Oxide           5.00                                                      Stearic Acid         2.50                                                      2,2'-Dithiobisbenzothiazole                                                                         0.75                                                      Tetramethyl Thiuram Disulfide                                                                       0.40                                                      ______________________________________                                    

The high-cis 1,4-polybutadiene may include FIRESTONE DIENE 600, 635, 645 or 660.

Another preferred 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber       40.00                                                     Very High-Cis 1,4-Polybutadiene                                                                     60.00                                                     Zinc Oxide           5.00                                                      Stearic Acid         2.50                                                      2,2'-Dithiobisbenzothiazole                                                                         0.75                                                      Tetramethyl Thiuram Disulfide                                                                       0.40                                                      ______________________________________                                    

The high-cis 1,4-polybutadiene may include Goodyear BUDENE 1207 or 1208.

Another preferred 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber         10.00                                                   1,4-Polybutadiene (KBR01 - 95-98% cis)                                                                90.00                                                   Zinc Oxide             5.00                                                    Stearic Acid           2.50                                                    Sulfur                 6.00                                                    Almax MBS              1.25                                                    DOTG                   0.75                                                    Agerite Super Lite     1                                                       Van Fre AP2            1.5                                                     ______________________________________                                    

DOTG and Almax are slower accelerants. The higher amount of zinc oxide adds strength to the invented composition without reducing energy return.

Another preferred 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber         10.00                                                   1,4-Polybutadiene (KBR01 - 95-98% cis)                                                                90.00                                                   Zinc Oxide             5.00                                                    Stearic Acid           2.50                                                    Sulfur                 6.00                                                    Almax MBS              1.25                                                    DOTG                   0.75                                                    Agerite Super Lite     1                                                       Van Fre AP2            1.5                                                     ______________________________________                                    

Another preferred 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber     90.00                                                       1,4-Polybutadiene (KBR01)                                                                         10.00                                                       Zinc Oxide         5.00                                                        Stearic Acid       2.50                                                        Sulfur             6.00                                                        Altax/MBTS         0.75                                                        M.Tuads/TUEX       0.40                                                        ______________________________________                                    

Another preferred 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber           90.00                                                 1,4-Polybutadiene (FIRESTONE DIENE 55NFA)                                                               10.00                                                 Zinc Oxide               5.00                                                  Stearic Acid             2.50                                                  Sulfur                   6.00                                                  Altax/MBTS               0.75                                                  M.Tuads/TUEX             0.40                                                  ______________________________________                                    

A preferred foam 1,4-polybutadiene/rubber composition comprises by weight:

    ______________________________________                                         Natural Rubber           40.00                                                 1,4-Polybutadiene (FIRESTONE DIENE 55NFA)                                                               10.00                                                 Zinc Oxide               6.00                                                  Stearic Acid             2.50                                                  Sulfur                   2.00                                                  2,2'-Dithiobisbenzothiazole                                                                             0.75                                                  Tetramethyl Thiuram Disulfide                                                                           0.40                                                  CELOGEN OT               0.16                                                  ______________________________________                                    

FIRESTONE DIENE 55AC10 (1,4-polybutadiene) may also be used in this embodiment of the invention.

Pre-Mixing

Since the several processes by which the 1,4-polybutadiene/rubber composition is manufactured utilize the same or substantially similar pre-mix formulations, the pre-mixing phases will now be described.

1,4-polybutadiene, as a raw material, is commercially available in bales or blocks weighing approximately 70 pounds. The 1,4-polybutadiene is softened and masticated (churned or chewed up). Softening and mastication are best accomplished in a commercially-available Banbury mixer where the 1,4-polybutadiene is mixed with a rubber selected from the group consisting of natural rubber, synthetic isoprene rubber, polyisoprene, butadiene acrylonitrile rubber and ethylene-propylene diene modified rubber. The rubber, in an uncured state, is first placed in the Banbury mixer in solid form, e.g., in 3" solid strips. The 1,4-polybutadiene is then added to the Banbury mixer. For example, the 1,4-polybutadiene may be cut into 3" strips from one or more of the above-mentioned bales. The entire mixture is then cross-cut, chewed up, softened and mixed by the Banbury rollers. After the 1,4-polybutadiene and rubber are sufficiently mixed, this pre-mixed composition has a putty-like consistency.

Cross-linking has been found to be a function of both elevated temperatures and pressure applied to the mix by which the compositions are cured. Cross-linking of the 1,4-polybutadiene and rubber of the pre-mix under high pressure and high temperature produces a durable, high energy return 1,4-polybutadiene/rubber composition having good tensile strength. To accomplish this within commercially acceptable times, certain commercially available and well known additives are introduced into the pre-mix described above. Specifically, commercially-available activating, accelerating, and curing agents are introduced as part of the pre-mix, in a collective amount usually not in excess of 10% by total weight of the 1,4-polybutadiene and the rubber. Preferably, a sulfur curing agent is acted upon by zinc oxide and stearic acid as activating agents. Examples of suitable accelerators may include, but are not limited to, tetramethyl thiuram disulfide, zinc dibutyldithiocarbamate and 2,2'-dithiobisbenzothiazole. The activators and accelerators become active in the process when heat, usually in excess of 300° F. for rapid curing, is applied.

Following cross-linking, the mixture is calendered, as described below. Calendering is preferably performed within one day of forming the cross-linked mixture.

Method No. 1

In the preferred method, the above-described pre-mix (including the curing, activating and accelerating agents) is removed from the Banbury mixer and placed as a layer of desired thickness, usually in excess of 1/4", on a commercially-available cold mill.

This layered material is then fed from the cold mill into and through a commercially-available calendering mill which has been preheated to 240° F. The calendered material is extruded from the calendar mill rollers at great pressure (e.g., 4,000 psi) to the desired thickness, e.g., 1/16" to 1/8". The material comes out of the calendering mill as a continuous sheet having a predetermined width, e.g., 38", and is continuously wrapped around a storage roller onto cellophane and nylon stripping. The wrapping continues until a roll of suitable length has collected on the storage roller. The roll may be, for example, from 1/16" to 1/4" thick, 38" wide, and from 40 to 200 feet long.

The roll is then taken to a pressure-applying autoclave and placed under heat (e.g., 307° F.) and pressure (e.g., 60 psi), for 4-5 hours to cure the roll. The heat and pressure cause the cellophane to contract around the roll. Afterwards the stripping is removed, and the cured high strength, high energy return material is re-rolled and placed in inventory.

Method No. 2

While this method is described in conjunction with the foam 1,4-polybutadiene/rubber composition, it is to be appreciated that, with the exception of a suitable gas entrainment additive, this method may be practiced to create either a foam or the substantially solid 1,4-polybutadiene/rubber composition.

If a foam 1,4-polybutadiene/rubber composition is desired, a suitable gas entrainment additive (foaming agent), such as 80% CELOGEN OT (generically referred to as p,p'-oxybisbenzene sulfonyl hydrazide, OBSH) (Uniroyal Chemical Company) or 800 GWP Master Mix (Master Processing, 2500 Thompson Street, Long Beach, Calif., 90801) is added to the pre-mix in amounts, for example, of 0.30 pounds per 188.8 pounds of premix or 11.0 pounds per 188.8 pounds of premix, respectively. The pre-mix is further mixed and layered to a desired pre-cured thickness in a cold mill. The desired pre-cured thickness will be slightly greater than the desired cured thickness, e.g., 5/16" and 1/4", respectively.

The sheet material obtained from the cold mill is cut into individual pieces sized to fit into a steel tray. An 18"×18" tray is satisfactory. The tray, carrying the sized material, is placed into a commercial hydraulic heat press and subjected to a continuing high temperature, e.g., within the range of 310-320° F., under a uniformly applied press-imposed pressure, e.g., about 2000 psi, for about 20-30 minutes. The substantially solid 1,4-polybutadiene/rubber composition requires 10 minutes.

The fully cured tray-carried material is then removed from the heat press and placed in inventory, ready to be cut into shoe components.

Method No. 3

A commercial Rotocure (heated mills placed in series) is pre-heated, e.g., to about 310° F. The above-described pre-mix is fed into and through the Rotocure unit as a continuous layer or belt, where the heat (of about 310° F.) and the roller pressure (of about 4000 psi or more) are applied as the belt of pre-mix is displaced therethrough. A continuous sheet of cured material issues from the Rotocure for placement in inventory, ready to be cut into shoe components.

Alternatives

In lieu of a Banbury mixer, the pre-mix can be mixed on a mill. A Banbury mixer, however, is much quicker (5 to 10 minutes vs. 30 minutes) and is consequently much less expensive. Temperature and pressure may be varied to cure the materials of this invention to provide a high energy return 1,4-poly-butadiene/rubber composition, depending upon time constraints.

While the foam and substantially solid 1,4-polybutadiene/rubber compositions described above have been correlated to shoe components, it is to be appreciated that these materials have application to other areas, such as gymnastics and basketball floors, and artificial football fields.

In other preferred embodiments of the method, a pre-mix of the 1,4-polybutadiene/rubber composition can be encapsulated in the sole of a shoe before vulcanization, as is known to those of skill in the art.

D. Energy Return

In the preferred embodiments of the invention, it is desirable to maximize the energy return of the composition. The energy return can be measured as Bashore Resilience by vertical rebound (ASTM D2632) using a button of the test material.

In some preferred embodiments of the invention, other materials may be included in the shoe component to provide additional features including, but not limited to, color, textures, added structural integrity and wear resistance. Such additional materials preferably do not decrease the energy return of the composition. Similarly, in the most preferred embodiments of the invention, the composition is substantially free of fillers (non-energy returning materials) which reduce the energy return of the shoe component below the claimed energy return. Such fillers include materials such as calcium carbonate, furnace black, pine tar, clays and silicas. Low energy return plastics and rubbers, such as 1,2-polybutadiene, are also preferably excluded from the 1,4-polybutadiene/rubber composition for the same reasons.

Comparative testing reveals that the instant invention provides substantially greater energy return than prior shoe components. Referring to Table 2, conventional EVA insoles (Comparative Example 1) produce a 12% energy return. When a layer of conventional shoe fabric is placed on top of an EVA insole, the energy return of the shoe component decreases (Comparative Example 2). In contrast, a foam 1,4-polybutadiene/rubber composition, having about 60 weight percent 1,4-polybutadiene (about 90% cis content) and about 40 weight percent natural rubber, provides about 47% energy return (Example 3). A substantially solid 1,4-polybutadiene/rubber composition, of about 60 weight percent 1,4-polybutadiene (about 90% cis content) and about 40 weight percent natural rubber, provides increased energy return of about 67% (Example 4). Example 5 shows that the combination of a substantially solid 1,4-polybutadiene/rubber composition with a layer of conventional shoe fabric on top is within the scope of the invention. Although the shoe fabric can act to somewhat reduce the energy return (compare Examples 4 and 5), substantial energy return is still conferred by this embodiment of the invention. When non-energy returning materials, such as pine tar and furnace black, are included in the composition, the energy return is substantially reduced (compare Examples 4 and 9).

Example 6 shows that the energy return of the foam 1,4-polybutadiene/rubber composition of Example 3 can be increased from about 47% to about 53% by adding a thin coating of hard polyurethane to the top or bottom of the 1,4-polybutadiene/rubber composition. Example 7 shows an increase in energy return from a substantially solid 1,4-polybutadiene/rubber composition comprising about 60 weight percent high-cis 1,4-polybutadiene and about 40 weight percent natural rubber. This embodiment of the invention yields increased energy return of 73%. Example 8 shows that the energy return is further increased by replacing the high-cis 1,4 polybutadiene with a very high-cis 1,4-polybutadiene.

E. Enhancement of Athletic Performance

Experimentation with various configurations and embodiments of the present invention has produced evidence establishing that an improvement in energy return, and athletic performance, is experienced by athletes using the 1,4-polybutadiene/rubber composition. More specifically, the length of stride on the first stride and successive strides in running, the jumping ability of a basketball player, and any combination of vertical and horizontal self-displacement by the user are enhanced. Several different measures of athletic performance were used to quantitate the improvement in athletic performance by shoe components comprising the 1,4-polybutadiene/rubber composition.

Study I. Double Blind Speed Study

In a double-blind speed study, thirty-one (31) athletes were speed tested for distances of 10, 20, 30 or 40 meters(M). A moleskin placebo or a substantially solid 1,4-polybutadiene/rubber insert (5/64 inches thick) was placed under the ball of the foot beneath the insole of the athlete's track spikes or running flats. The participating athletes were not informed that either the placebo or the insert could increase athletic performance. The 1,4-polybutadiene/rubber composition comprised about 60 weight percent 1,4-polybutadiene (about 90% cis content) and about 40 weight percent natural rubber. The athletes were members of either university track, baseball and football teams or national track and soccer teams. For each athlete, one to four time trials were conducted over a one or two day period. The athletes were tested on both outdoor and rubberized tracks. The speed improvements of the athletes, as measured in seconds, are shown in Table 3.

Example 1 shows the speed improvements of athletes for a distance of 40 meters while wearing running spikes. From a standing start, the athletes' times were measured at 10 and 40 meters. The time difference between 10 and 40 meters was used to compute the time the athletes took to traverse the intermediate 30 meters. As shown in Example 1, when the athletes wore running spikes containing a insert according to the invention, their average improvement was about 1.57-1.59%, and the speed improvement was nearly constant throughout the 40 meter distance.

Example 2 shows speed improvements of athletes for a distance of 20 meters while wearing running flats. From a standing start, the athletes' times were measured at 10 and 20 meters. The time difference between 10 and 20 meters was used to compute the time the athletes took to traverse the second 10 meters. As shown in Example 2, the average speed improvement of the athletes was greater for the second 10 meters as compared with the first 10 meters (0.61% vs 1.58%; compare 2a and 2b). The speed improvement of the athletes was less pronounced during their initial acceleration than once they had reached full stride. The average improvement for the second 10 meters, of about 1.58%, was very similar to the average speed improvement observed in Example 1a-c, and indicates that the speed improvement can be independent of the shoe type.

Example 3 shows the speed improvements of athletes wearing running spikes. From a standing start, the athletes' times were measured for a distance of 20 meters. The observed average speed improvement of 1.36% is very similar to the speed improvements of the athletes in Example 1 and Example 2b.

Of the athletes tested in Examples 1-3, twenty-six (26) ran significantly faster, two (2) ran slower and three (3) ran statistically the same. This study also showed that athletes wearing both track spikes and running flats can experience improved athletic performance.

Study II. Seasonal Performance Testing

A seasonal study of fourteen (14) members of university track teams was conducted to evaluate the performance of athletes with and without a 1,4-polybutadiene/rubber insert. The 1,4-polybutadiene/rubber insert (5/64" thick) comprised 60 weight percent 1,4-polybutadiene (about 90% cis content) and 40 weight percent natural rubber, and was built into the athletes' meet spikes below the ball of the foot under the insole. The athletes were divided into two groups. The average and best performances of these athletes are shown in Tables 4 and 5, respectively.

For Group 1, the average and best athletic performances of eight (8) sprinters (100 to 400 meter runs and intermediate hurdle events) were monitored for a nine week period without the invented insert, and for a three week period with the invented insert, in their meet spikes. Seven (7) of the eight (8) athletes showed improved average and best performances with the present invention in their shoes. The average improvement for this group was 1.49%.

For Group II, the average and best athletic performances of six (6) middle-distance runners (800 and 1500 meters runs) were monitored for a two month period without the insert, or a one month period with the insert, in their meet spikes. All six (6) athletes showed improved average and best performances with the insert in their shoes. The average improvement for the middle-distance runners was 1.48%.

Thus, thirteen of fourteen athletes participating in this study showed an average performance improvement of 1.48-1.49% using the present invention. This performance improvement is very similar to the performance improvement of the athletes shown in the double blind speed study (Study I.) of 1.36-1.59%. In contrast, sixty (60) percent of athletes (50 athletes in 42 of 70 events) in a control group (without the insert) showed no improvement in athletic performance over the same time period.

Study III. Two Leg Double Bound Tests

A two leg double bound test was conducted on 35 members of university volleyball, baseball and track teams. The distances the athletes could jump, from a standing start, in two sequential jumps was measured with and without a insert inserted in the athletes' shoes. The insert comprised 60 weight percent 1,4-polybutadiene (about 90% cis content) and 40 weight percent natural rubber; the insert was placed in the athletes' shoes below the ball of the foot under the insole. These athletes were able to jump an average of 21/2, 21/2 and 5 inches farther, respectively, when the invented insert was used. The range of improvements was from -2" to 14", when the invented insert was used.

Study IV. Two Leg Double Bound Tests

A two leg double bound test was also conducted using a insert comprising 60 weight percent high-cis 1,4-polybutadiene and 40 weight percent natural rubber in the form of an insert placed in the athletes' shoes below the ball of the foot under the insole. Of twelve (12) members of a division 1 university basketball team, all jumped farther with the insert placed in the shoe. The average improvement in distance was 5.6 inches. The range of improvements was from 1 to 12 inches.

Fourteen (14) members of a high school varsity volleyball team were also tested. All fourteen athletes jumped farther with the insert in their shoe. The average improvement was 8.6 inches, when the invented pad was used. The range of improvements was from 31/2 to 14 inches, when the invented pad was used.

Study V. Two Leg Double Bound and Vertical Jump Tests

A two leg double test of university high jumpers and triple jumpers, track and basketball players and volleyball players was conducted using a insert of 60 weight percent very high-cis 1,4-polybutadiene and 40 weight percent natural rubber in the form of a insert inserted in the athletes' shoes below the ball of the foot under the insole. Of five (5) high and triple jumpers, the improvement in the length of the double bound jump ranged from 5 to 15 inches, with an average increase of about 9.6 inches. Similarly, four (4) members of the same group showed an increase in the height of a vertical jump ranging from 1.5 to 4.5 inches, with an average of about 2.8 inches.

Twelve (12) members of a university track and basketball teams were also tested. Of the twelve (12) athletes participating in the double bound test, the increases in jump length ranged from 4.5 to 12 inches, with an average increase of about 7.8 inches. Of the four (4) athletes participating in the vertical jump test, the increases in jump height ranged from 3-4 inches, with an average increase of about 3.25 inches.

Eight (8) members of a university men's volleyball team were similarly tested. The athletes showed an increase in the jump length of the double bound test ranging from 2 to 14 inches, with an average of about 8 inches. Of the four (4) athletes participating in the vertical jump test, the increase in jump height ranged from -1 to 3 inches, with an average increase of about 1.9 inches.

                  TABLE 1                                                          ______________________________________                                         Shoe Components                                                                Ex-   Shoe      1,4-Polybutadiene                                                                            Rubber                                           ample Component (weight percent)                                                                             (weight percent)                                 ______________________________________                                          1    solid sole                                                                               46% 1,4-polybutadiene                                                                        54% polyisoprene                                  2    foam insole                                                                              50% 1,4-polybutadiene                                                                        50% acrylonitrile                                                              butadiene                                         3    solid midsole                                                                            54% 1,4-polybutadiene                                                                        45% ethylene propylene                                           (high-cis)    diene modified rubber                             4    foam insole                                                                              75% 1,4-polybutadiene                                                                        25% synthetic isoprene                            5    solid insole                                                                             70% 1,4-polybutadiene                                                                        30% synthetic isoprene                                           (high-cis)                                                      6    foam      95% 1,4-polybutadiene                                                                        5% natural rubber                                      midsole                                                                   7    foam insole                                                                              70% 1,4-polybutadiene                                                                        30% acrylonitrile                                                (high-cis)    butadiene                                         8    solid insole                                                                             60% 1,4-polybutadiene                                                                        40% natural rubber                                9    solid insole                                                                             60% 1,4-polybutadiene                                                                        40% natural rubber                                               (high-cis)                                                     10    solid insole                                                                             95% 1,4-polybutadiene                                                                        5% polyisoprene                                  11    solid insole                                                                             60% 1,4-polybutadiene                                                                        40% natural rubber                                               (very high-cis)                                                12    solid midsole                                                                            70% 1,4-polybutadiene                                                                        30% natural rubber                                               (very high-cis)                                                13    solid insole                                                                             75% 1,4-polybutadiene                                                                        25% natural rubber                                               (very high-cis)                                                14    solid midsole                                                                            50% 1,4-polybutadiene                                                                        50% natural rubber                                               (very high-cis)                                                15    solid insole                                                                             100% 1,4 poly-                                                                               n/a                                                              butadiene                                                                      (very high-cis)                                                ______________________________________                                    

                  TABLE 2                                                          ______________________________________                                         Energy Return                                                                                                  Energy                                         Example  Composition (Weight Percentage)                                                                       Return                                         ______________________________________                                         Comparative                                                                             EVA sponge rubber insole                                                                              12%                                            Example 1                                                                               with shoe fabric removed                                              Comparative                                                                             EVA sponge rubber insole                                                                              10%                                            Example 2                                                                               with shoe fabric on top                                               3        foam 1,4-polybutadiene/rubber composition                                                             47%                                                     (60% 1,4-polybutadiene (90% cis), 40%                                          natural rubber with a foaming agent)                                  4        substantially solid 1,4-polybutadiene/-                                                               67%                                                     rubber composition (60% 1,4-poly-                                              butadiene (90% cis), 40% natural rubber)                              5        substantially solid 1,4-polybutadiene/-                                                               56%                                                     rubber composition with shoe fabric on top                                     (60% 1,4-polybutadiene (90% cis), 40%                                          natural rubber)                                                       6        foam 1,4-polybutadiene/rubber composition                                                             53%                                                     with 1/16" of polyurethane coating                                             (60% 1,4-polybutadiene (90% cis), 40%                                          natural rubber)                                                       7        substantially solid 1,4-polybutadiene/-                                                               73%                                                     rubber composition (60% 1,4-polybutadiene                                      (95% cis), 40% natural rubber)                                        8        substantially solid 1,4-polybutadiene/-                                                               75%                                                     rubber composition (60% 1,4-polybutadiene                                      (98% cis), 40% natural rubber)                                        Comparative                                                                             Composition of Example 4 with one-third by                                                            45%                                            Example  total weight of rubber furnace black and                              9        pine tar.                                                             ______________________________________                                    

                                      TABLE 3                                      __________________________________________________________________________     Double Blind Speed Study                                                            Number of                                                                 Example                                                                             Athletes                                                                            Shoes  Distance                                                                            Average Improvement                                                                       Comments                                      __________________________________________________________________________     1a   14   Track Spikes                                                                          10 M 0.0224 seconds (1.58%)                                                                    First 10 M                                    b    14   "      30 M 0.0505 seconds (1.57%)                                                                    Second 30 M                                   c    14   "      40 M 0.0729 seconds (1.57%)                                                                    Total Distance                                2a   14   Running Flats                                                                         10 M 0.0108 seconds (0.61%)                                                                    First 10 M                                    b    11   "      10 M 0.0198 seconds (1.58%)                                                                    Second 10 M                                   c    11   "      20 M 0.0275 seconds (0.88%)                                                                    Total Distance                                3     3   Track Spikes                                                                          20 M 0.0357 seconds (1.36%)                                                                    Total Distance                                __________________________________________________________________________

                  TABLE 4                                                          ______________________________________                                         Average Seasonal Improvement                                                                     Average   Average Average                                    Example                                                                               Event      without pad*                                                                             with pad*                                                                              Improvement                                ______________________________________                                         Group 1                                                                        A.     400 M Run  48.30 (1) 47.59 (3)                                                                              0.71 seconds                                                 46.81 (5) 46.03 (2)                                                                              0.78 seconds                                                 48.35 (5) 47.27 (4)                                                                              1.08 seconds                               B.     400 M Hurdles                                                                             52.17 (6) 50.59 (3)                                                                              1.58 seconds                               C.     200 M Run  21.94 (1) 21.49 (2)                                                                              0.45 seconds                                                 20.97 (1) 20.8  (1)                                                                              0.17 seconds                                                 21.60 (1) 21.38 (2)                                                                              0.22 seconds                                                 21.54 (1) 21.27 (1)                                                                              0.27 seconds                               D.     110 M Hurdles                                                                             14.51 (3) 14.29 (4)                                                                              0.22 seconds                                                 14.14 (8) 13.91 (2)                                                                              0.23 seconds                               E.     100 M Run  10.66 (4) 10.73 (6)                                                                              -0.07 seconds                              F.     Long Jump  22'10" (5)                                                                               23'4" (5)                                                                              6" farther                                 Group II.                                                                      G.     1500 M Run 357.56 (4)                                                                               354.15 (2)                                                                             3.41 seconds                                                 358.24 (3)                                                                               355.27 (2)                                                                             2.97 seconds                                                 357.60 (3)                                                                               355.85 (2)                                                                             1.75 seconds                               H.     800 M Run  154.51 (1)                                                                               153.50 (3)                                                                             1.01 seconds                                                 153.40 (3)                                                                               151.93 (4)                                                                             1.47 seconds                                                 156.94 (4)                                                                               154.00 (4)                                                                             2.94 seconds                               ______________________________________                                          *The average improvement for all examples except F is given in seconds.        The number of trials used to compute the average is shown in parentheses.

                  TABLE 5                                                          ______________________________________                                         Best Seasonal Performance                                                                        Average   Average                                            Example                                                                               Event      without pad*                                                                             with pad*                                                                              Improvement                                ______________________________________                                         Group 1                                                                        A.     400 M Run  48.30 (1) 47.34 (3)                                                                              0.96 seconds                                                 45.82 (5) 45.96 (2)                                                                              -0.14 seconds                                                47.81 (5) 47.03 (4)                                                                              0.78 seconds                               B.     400 M Hurdles                                                                             51.41 (6) 50.45 (3)                                                                              0.96 seconds                               C.     200 M Run  21.94 (1) 21.38 (2)                                                                              0.56 seconds                                                 20.97 (1) 20.8  (1)                                                                              0.17 seconds                                                 21.60 (1) 21.31 (2)                                                                              0.29 seconds                                                 21.54 (1) 21.27 (1)                                                                              0.27 seconds                               D.     110 M Hurdles                                                                             14.38 (3) 14.17 (4)                                                                              0.21 seconds                                                 13.91 (8) 13.88 (2)                                                                              0.03 seconds                               E.     100 M Run  10.56 (4) 10.54 (6)                                                                              0.02 seconds                               F.     Long Jump  24'1" (5) 24'1" (5)                                                                              --                                         Group II.                                                                      G.     1500 M Run 356.33 (4)                                                                               351.93 (2)                                                                             4.41 seconds                                                 357.94 (3)                                                                               353.83 (2)                                                                             4.11 seconds                                                 356.33 (3)                                                                               351.06 (2)                                                                             5.27 seconds                               H.     800 M Run  154.51 (1)                                                                               152.86 (3)                                                                             1.65 seconds                                                 151.93 (3)                                                                               150.60 (4)                                                                             1.33 seconds                                                 154.96 (4)                                                                               152.92 (4)                                                                             2.04 seconds                               ______________________________________                                          *The average improvement for all examples except F is given in seconds.        The number of trials from which the best performance was selected is show      in parentheses.                                                          

SUMMARY

In summary, athletes and coaches using the present invention of a 1,4-polybutadiene/rubber composition experienced unexpected increases in athletic performance. Most athletes experienced increased faster running times of up to about 1.6%, and further speed increases are contemplated with regular use of the present invention. Similarly, most athletes were able to jump farther with the present invention than without the invention. Athletes and coaches commented that such a insert would be invaluable to enhance performance, and that they had never used such a performance enhancing shoe component before. They also commented that the present invention would also be expected to reduce or mitigate injuries.

While the present invention has been described and illustrated in conjunction with a number of specific embodiments, those skilled in the art will appreciate that variations and modifications may be made without departing from the principles of the invention as herein illustrated, described and claimed.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are to be considered in all respects as illustrative, and not restrictive. The scope of the invention, is therefore, indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

I claim:
 1. A performance-enhancing shoe component, comprising:a first layer shaped for placement within a shoe, said first layer having a ball portion, said first layer comprising a cured mix of:(i) 1,4-polybutadiene having a cis content of at least about 90%, the amount of said 1,4-polybutadiene ranging from greater than 46 to about 95 weight percent, and (ii) rubber selected from the group consisting of natural rubber, synthetic isoprene rubber and polyisoprene, the amount of said rubber ranging from less than 54 to about 5 weight percent; said ball portion of said first layer providing at least 47% energy return, said first layer having surface texturing that increases energy return; wherein said weight percentages are based on the total weight of said 1,4-polybutadiene and said rubber; and wherein said first layer is substantially free of fillers and non-energy-returning rubber which reduce energy return.
 2. A shoe component according to claim 1,wherein said cured mix is substantially solid and substantially free of trapped gas.
 3. A shoe component according to claim 1,wherein said rubber in said first layer is natural rubber.
 4. A shoe component according to claim 1, further comprising:a resilient layer attached to said first layer and shaped for placement within a shoe, said resilient layer extending substantially the length of a shoe, said resilient layer comprising a material selected from the group consisting of styrene butadiene rubber, neoprene, natural rubber and polyurethane.
 5. A shoe component according to claim 1,wherein said 1,4-polybutadiene has a cis content of at least about 95%.
 6. A shoe component according to claim 5,wherein said 1,4-polybutadiene is very high-cis 1,4-polybutadiene having a cis content of at least about 98%.
 7. A shoe component according to claim 4,wherein said resilient layer is natural rubber.
 8. A shoe component according to claim 4,wherein said resilient layer is styrene butadiene rubber.
 9. A shoe component according to claim 1,wherein said first layer extends substantially the length of the shoe.
 10. A shoe component according to claim 4, further comprising:a coating disposed on the top of said resilient layer, said coating receiving a force transmitted from a user's foot on a given surface area of said coating, and transmitting at least a portion of said force to a greater surface area of said resilient layer.
 11. A shoe component according to claim 10,wherein said coating is selected from the group consisting of neoprene, styrene butadiene rubber, natural rubber and polyurethane.
 12. A shoe component according to claim 4, further comprising:(c) a third layer shaped for placement within a shoe and beneath the ball of a human foot, said third layer disposed on top of said resilient layer, said third layer selected from the group consisting of styrene butadiene rubber, neoprene, polyurethane and natural rubber.
 13. A shoe component according to claim 1,wherein said first layer has 1,4-polybutadiene ranging from greater than 75 to about 95 weight percent, and rubber ranging from less than 25 to about 5 weight percent.
 14. A shoe component according to claim 4,wherein said resilient layer has surface texturing that provides additional energy return.
 15. A shoe component according to claim 12,wherein said third layer has corrugations which provide additional energy return.
 16. A performance-enhancing shoe component, comprising:(a) a first layer shaped for placement within a shoe and beneath the ball of a human foot, said first layer having a ball portion, said first layer comprising a cured mix of:(i) 1,4-polybutadiene having a cis content of at least about 90%, the amount of said 1,4-polybutadiene ranging from greater than 75 to about 95 weight percent, and (ii) rubber selected from the group consisting of natural rubber, synthetic isoprene rubber and polyisoprene, the amount of said rubber ranging from less than 25 to about 5 weight percent; (b) a second layer which extends substantially the length of a shoe, said second layer having a ball portion, said first layer being attached to said second layer at said ball portion, said second layer comprising a material selected from the group consisting of neoprene, natural rubber, foamed polyurethane and ethylene vinyl acetate-natural rubber mix;wherein said weight percentages are based on the total weight of said 1,4-polybutadiene and said rubber; wherein said first layer is substantially free of fillers and non-energy-returning rubbers which reduce energy return; wherein said ball portion provides at least 47% energy return; said first layer having surface texturing that increases energy return.
 17. A shoe component according to claim 16,wherein said cured mix is substantially solid and substantially free of trapped gas.
 18. A shoe component according to claim 16,wherein said rubber is natural rubber. 